1. Scientific Measurement

2. Scientists prefer QUANTITATIVE as there is no room for bias!
Types of measurement
Quantitative- use numbers to describe
Qualitative- use description without numbers
4 feet
extra large
Hot
100ºF
Scientists prefer QUANTITATIVE as there is no room for bias!

3. Remember…
Numbers without units are meaningless.
NO NAKED NUMBERS!!!

4. How good are measurements?
Accuracy- how close the measurement is to the true value
Precision- how well can the measurement be reproduced

5. Let’s use a golf analogy

6. Accurate? No
Precise?
Yes

7. Accurate?
Yes
Precise?
Yes

8. Precise? No
Accurate? No

9. Accurate?
Yes
Precise?
We can’t say!

10. Significant figures (sig figs)
How many numbers in a measurement means something
When we measure something, we can (and do) always estimate between the smallest marks. 2 1 3 4 5

11. Significant figures (sig figs)
More marks = More precision Scientists always understand that the last number measured is actually an estimate 1 2 3 4 5

12. Sig Figs
Since science tools aren’t precise to infinite digits, we say only certain numbers are “significant” to us.

13. Atlantic/Pacific Rule
Number
Pacific
Atlantic
If decimal is “Present” start counting from the Pacific
Side at the first “non-zero” digit and continue counting
until the number ends.
If the decimal is “Absent” start counting from the
Atlantic side at the first “non-zero” digit and continue
counting until the number ends.

14. How many sig figs in these measurements?3
#2: g
#3: g
#4: g 9

15. Which measurement has 3 sig figs?
2.013
4200
74.0
830

16. Round the following numbers to three sig figs. #1: 47. 389 47

17. Determine the number of significant figures for each number:
461728
14.91
3.5810
5.2631
22.101
23.1
0.9307

18. Answers: Determine the number of significant figures for each number
23.1 3

19. More Practice
1234
0.023
1000
890
91010
0.0001
9010.0
8120 72

20. Answers: More Practice
890 2
72 2